U.S. Pat. No. 5,250,179 discloses a filter element for use in a fluid filter of the type in which the fluid to be filtered is caused to pass radially outwardly through the filter element, said filter element comprising a web of pleated filtering material that is formed into a circumferentially closed cylindrical filter body, which is coaxially supported by a perforate rigid tube surrounding said body and the axial ends of which are sealingly inserted into corresponding annular receiving cavities provided in a rigid bottom end cap at one end and in a rigid annular end cap at the opposite end of the filter body. With this well-known filter element both the rigid bottom-end cap and the rigid annular end cap are fixedly bonded to the axial ends of the cylindrical filter body, thereby assuring that the filter element is completely fluidtight at the ends, so that in use no fluid (including contaminants!) can flow from the space within the cylindrical filter body between the axial ends of the filter body and the rigid bottom end cap or annular end cap towards the exterior of the filter body and vice versa. The cylindrical filter body and the two end caps form a sub-assembly that is adapted to be removably placed into the perforate support tube. The latter is closed by a separate bottom end cap at one end and is provided with an outwardly extending flange at the opposite end, said flange being adapted to sealingly engage an annular lip that extends radially outwardly from the rigid annular end cap, and to be sealingly clamped, together with said lip, onto a support within the housing of the fluid filter.
When, in use, a certain degree of blockage of the filter element has been reached, the element has to be removed from the filter housing or filter chamber for replacement.
From a viewpoint of damage to the environment it is an advantage of the well-known filter element that only the sub-assembly needs to be replaced and is considered as waste and treated accordingly, whereas the perforate support tube can be reused after having placed therein a new sub-assembly.